Hello NeXT Community: Apologies for not posting , my dad's is been in the ICU for 3 weeks , today he has finally moved to a regular bed long story.
I thought you all may have an opinion on what I have stumbled upon. I found I had some old Apple 512K 64 pin rom's from 1988, thought huh , NeXT DSP is 64 pin , the idea of the Apple was to address 32 bit upgrade from earlier 24 . I said what is the worst that can happen lol , well no fireworks check out video she boots. Now I'm trying figure out if it is actually doing something https://youtu.be/rgmYGCdPCO4 , so now to look for bench marks or something , any help appreciated ,
I bought 2 more from eBay ,they are from 89 , may be I'm onto something as I seem recall wayback hearing about this I swear stuff warps in here all the time .
Now I am in a unique position to test it with my original NeXT dsp expansion chip as well and with no chip in the expansion slot .

May be our answer was hiding in plain site this whole time .
If they are dormant and in place can they simply be reprogrammed?

Brian, helped me out on this one as apparently it is the same packaging but electrically not compatible with NeXT . SO a NO GO?

Hello NeXT Community: Apologies for not posting , my dad's is been in the ICU for 3 weeks , today he has finally moved to a regular bed long story.

Ouch. All the best...

Quote:

I thought you all may have an opinion on what I have stumbled upon. I found I had some old Apple 512K 64 pin rom's from 1988, thought huh , NeXT DSP is 64 pin , the idea of the Apple was to address 32 bit upgrade from earlier 24. I said what is the worst that can happen lol , well no fireworks check out video she boots.

The ROM SIMM itself won't work for the simple reason it's a ROM, not a RAM. Another difference is the bus width, the 68k needs 32 bit, the DSP56k has a 24 bit address bus.

Best,
Michael[/quote] Thanks I removed it from the NeXT DSP slot . Best Regards Rob Blessin_________________Rob Blessin President computerpowwow ebay sales@blackholeinc.comhttp://www.blackholeinc.com
303-741-9998 Serving the NeXT Community since 2/9/93

Last edited by Rob Blessin Black Hole on Mon Oct 16, 2017 10:31 am; edited 1 time in total

Now call me crazy but how programmable is the "rominator" so obviously we need 24 bit addressing not 32 what I'm getting at is it has a flash program would it be as simple as flashing
or rom burning it with the right code.
I've asked Steve:
If we can make modifications easily as it looks like he has a programmable chip solution and if rom to ram is emulation possible.
Steve has the 64Pin PCB template and a manufacturer in place to make 64 pin simms hopefully,

Hello NeXT Community:
I found this Kingston 64 pin ram stick , it is unusual as not a lot of 64 pin stuff apparently some 1989 Macs maybe used 64 pin ? My guess is this simm is Ram not ROM and probably cost $500 .
Question it was in with a bunch of NeXT stuff and
I pictured it NeXT to a NeXT DSP Chip obviously I don't want to smoke a board or the chip or both but would this possibly be compatible with the NeXT DSP expansion slot . I'm not trying to be stupid here but curious .
and

Steve Chamberlain and BMOW pointed me to a company that potantially will produce 64 pin simms , in small quantities, source the components and laser etch the custom pcb boards but the catch is I need a nice schematic for the DSP . Would anyone be able to clean up the DSP schematic in the archive or draw up what we need to make chip. I think now the technology has caught up to where we have a chance to make these for a reasonable price https://www.elecrow.com/pcb-assembly.html Any thoughts? Best Regards Rob_________________Rob Blessin President computerpowwow ebay sales@blackholeinc.comhttp://www.blackholeinc.com
303-741-9998 Serving the NeXT Community since 2/9/93

Hello NeXT Community:
I found this Kingston 64 pin ram stick , it is unusual as not a lot of 64 pin stuff apparently some 1989 Macs maybe used 64 pin ? My guess is this simm is Ram not ROM and probably cost $500

That's a DRAM SIMM for a Mac IIfx - completely different, sorry...

Quote:

Steve Chamberlain and BMOW pointed me to a company that potantially will produce 64 pin simms , in small quantities, source the components and laser etch the custom pcb boards but the catch is I need a nice schematic for the DSP . Would anyone be able to clean up the DSP schematic in the archive or draw up what we need to make chip. I think now the technology has caught up to where we have a chance to make these for a reasonable price https://www.elecrow.com/pcb-assembly.html Any thoughts? Best Regards Rob

The DSP SIMM ist's complicated - I can try to convince one of my students to design one (would do it myself, but I don't have that much free time at the moment). The SFSU board uses a four-layer design, that will make the PCB a bit more expensive. Perhaps we can get a two-layer board to work.

The RAMs themselves are simply 32 k x 8 or 128 k x 8 SRAMs (giving 96 or 384 kB extra memory, since the 56k memory bus is 24 bits wide - or twice the amount if separate RAMs for program and data space are used, as in the SFSU board). The only additional part on the SFSU DSP memory expansion board is a simple inverter.

A quick check of the inventory at mouser shows suitable SRAM chips (IDT 71024S20YGI8 20ns) available for less than 3€ in single quantities, the inverter (74ALS04) costs about 0.60€.

Here's a picture of a DSP56k memory expansion for some ancient Motorola eval board - I have a number of old DSP56k board in my lab here and even a 56k in-circuit emulator (which requires a PC with an ISA slot, however...).